Krieger suggests that Plainview lies between Folsom and Eden in its type of flint work. Later excavations may prove that the three points have a similar historical relationship, and may throw more light on some nine or ten other types of points that early man seems to have made.[28]
[Illustration: _Two points that resemble somewhat the Plainview type, and may indeed be merely deviations from it. The one at the left was found by a fisherman at Chinitna Bay, Alaska, and called by Hibben Yuma-like. The other was discovered by Jenks at Browns Valley, Minnesota, associated with a human skeleton. (Left, measurements not available, after Hibben, 1943; right, about natural size, after Roberts, 1940.)_]
[Illustration: FLINT KNAPPING OF THE OLD AND NEW STONE AGES
_From 5,000 to 10,000 years separate the Solutrean artifact of the Paleolithic period from the Neolithic work of Denmark and Egypt, depending on which time scale you accept. The Eden point may have been made 7,000 years ago or even nearer the Neolithic. (The Eden, after Howard, 1935; the Solutrean, after Sollas, 1911; the Danish, after Plant, 1942; the Egyptian, after De Morgan, 1925.)_]
Besides Clovis, Eden, and Plainview, Alaska has provided cores that Nelson finds “identical in several respects with thousands of specimens found in the Gobi Desert.” He recognizes them as evidence of migration from Asia 9,000 to 12,000 years ago.[29]
[Illustration: _A Gypsum Cave point. (After Roberts, 1940.)_]
After the discovery of the Eden point, the next important development came in 1930 with M. R. Harrington’s excavation of Gypsum Cave, Nevada. Here he found the dung, hair, skin, and bones of the ground sloth in clear association with a wide variety of artifacts. Besides the sloth, there were fossils of camel and perhaps horse. Among the artifacts was a new type of diamond-shaped point, and—quite as remarkable—there were parts of painted dart shafts with the butts pitted for use with a spear-thrower. In addition to knives and oval scrapers, there were fire hearths. Gypsum man burned sloth dung as well as wood, and used torches. Harrington dated the culture at about 10,500 years ago. Radiocarbon dates from sloth dung six feet four inches deep averaged 10,455 ± 340 years.[30] Similar material closer to the surface recorded 8,527 ± 250 years.[31] Thus Gypsum seems to follow Folsom.[32]